One of the most classic — and persistent — markers of the "all-American" beauty standard is a set of perfectly straight, blindingly white teeth. From the movie stars we find most attractive to the politicians we find especially trustworthy and composed, it's an ideal deeply ingrained in the fabric of our society: white teeth are desirable, which means yellow teeth are something to be fixed. It's so deeply ingrained, in fact, that it affects the way we treat and perceive those around us. 

There are studies that prove a set of gleaming pearly whites is a measurable social and professional advantage. For the people who possess this type of gleaming grin, that edge might look like more matches on your dating profile or skipping a few rungs on the corporate ladder. Simply put: The likelihood of success is tipped in your favor (even if that's just marginally) when your teeth are especially brilliant. It's no wonder that the teeth-whitening market is projected to hit a $11.66 billion dollar valuation by 2030. That's a whole lot of Crest Whitestrips. 

If, after hearing all this, you understandably  decide to pursue a whiter smile, you should know that there is actually a limit on just how much you can whiten your teeth — and that limit is different for everyone. That Hollywood white smile might be marketed as something that’s within reach for us all — at least according to various upbeat toothpaste commercials — but the reality is that your tooth shade was predetermined when you were born, and for some people, that means their smile is naturally yellow.

"Natural tooth color is determined by genetics, similar to hair or eye color," says New York City-based cosmetic dentist Victoria Veytsman, DDS. “We're limited to the natural upper limit of the teeth [when whitening].”

Meet the Experts:

• Victoria Veytsman, DDS, a cosmetic dentist and owner of Cosmetic Dental Studios in New York City.

• Sharon Huang, DDS, a cosmetic dentist and founder of Les Belles NYC Dentistry in New York City.

• E. Lisa Reid, DMD, a prosthodontist and partner at Integrated Aesthetic Dentistry in New York City.

Keep reading to learn what some of the industry's top dental experts have to say about why some people have whiter teeth than others — and what you can do to preserve — and love — your own best smile.

In this story:

• Why do some people have naturally white teeth?

• What causes tooth discoloration and staining?

• How does "tooth trauma," i.e. injuries, make them look darker or yellower?

• What is the maximum amount you can whiten your teeth?

• So, does this mean you're stuck with your tooth color?

Why do some people have naturally white teeth?

From the time you were in utero, the tone of your teeth was already established. That's due to the thickness of your enamel (the outer layer of your tooth), that enamel’s brightness, and the underlying dentin. "Teeth are made up of three layers," explains New York City-based cosmetic dentist Sharon Huang, DDS. "The nerve in the center, then dentin — which is a yellowish color — then enamel." All of these things are governed by your genetics, and they can all impact the color of your teeth. According to Dr. Huang, people who have thicker enamel and lighter dentin will have brighter teeth naturally.

E. Lisa Reid, DMD, a prosthodontist in New York City, explains further: "When you have thinner enamel, then more of the yellow dentin underneath shows through," adding that these variations are not just person to person, but tooth to tooth as well. "In general, the upper front teeth are more yellow in color when compared to the lower front teeth, and the two upper front teeth are brighter than the adjacent teeth on either side." 

There is also a shade spectrum for teeth, and none of those shades include the word "white." According to Dr. Reid, there are four basic color groups that your teeth can fall into: reddish brown, reddish yellow, gray, and reddish gray. "[A] tooth can range in the saturation of color along that spectrum," she clarifies.

This means some people simply possess teeth that appear super white from the very beginning, which means if these teeth do become stained, they'll be able to return to that color (for the most part, but more on that later).

What causes tooth discoloration or staining? 

You've likely heard that your teeth can get stained from habits like drinking coffee or eating acidic food, but that's just the tip of the yellowing iceberg. Intrinsic staining, which means staining the internal dentin layer of the teeth, could also be why your teeth have always appeared more yellow. Unlike extrinsic staining (the one for which you can blame red wine and which contributes to more superficial enamel staining) this type of staining is often beyond our control.

"[This type of] staining is more difficult to correct when the dentin becomes darker," says Dr. Reid. She explains that tetracycline and doxycycline antibiotic use at an early age, or use by expectant mothers during the second stage of pregnancy (which is when tooth development happens) can cause this type of staining in children's teeth. Additionally, "too much fluoride, either administered from over-fluoridated water sources or excessive ingestion of fluoride supplements during tooth development, may contribute to tooth discoloration by causing the development of white or brown spots or pitting of the enamel, which can darken over time." Dr. Reid adds.

Can "tooth trauma," i.e. injuries, make them appear darker or yellower?

Trauma to the teeth, such as dental injuries, can also impact their color. According to Dr. Veytsman, "Blunt force trauma aggravates the tooth's nerves and the nerves die. [A dead nerve] is like an internal bruise of the tooth and it can turn completely gray from the inside."

So, while you might feel lucky when you trip on the sidewalk or take a hockey puck to the face and come away with all your teeth, the impact can ultimately dull your teeth as the nerves start to die. (If this occurs, Dr. Veytsman explains that the tooth can be bleached from the inside out following a root canal).

What is the maximum amount that you whiten your teeth — both at home or at the dentist? 

Contrary to popular belief, you aren't boosting the actual whiteness of your teeth through professional whitening services or at-home products. Rather, Dr. Veytsman says that these services are just removing a buildup of stains that have accumulated over the years to expose your brightest natural color. These stains can be worsened by smoking, consuming staining food or beverages like blueberries, coffee, tea, wine, eating acidic foods, and not practicing quality oral hygiene. This means daily brushing with a toothbrush, flossing, using mouthwash, and seeing your dentist for annual or even biannual cleanings.

Everyday habits at home can also help or hurt your whitening efforts. Dr. Huang explains that nutrition also contributes to the tone of your teeth, stating that "mineral-dense foods can help result in whiter teeth. A malnourished child will see an effect in their teeth." Some toothpastes can also actually be working against you here, too: Although they were trendy for a few years, Dr. Reid adds that, "using abrasive toothpastes, such as charcoal toothpaste, [can] lead to thinning of the enamel, making the teeth appear darker as the dentin layer begins to show through more." 

All of these types of discoloration are known as extrinsic stains and only affect the outermost layer of the tooth, which is what teeth whitening services and products target. Although your teeth might look extra bright at the end of a professional treatment, it's not an effect that will last forever, nor will it withstand stains from certain lifestyle choices.

"All whitening is doing is using a gel that bonds to the stains. It oxidizes and removes the stains to bring back the natural color," says Dr. Huang. So if you return to the habits that stained your smile in the first place, you’ll eventually end up back in the same place color-wise. It also means that if your teeth were never super white to begin with, no amount of expensive whitening services (all of which use hydrogen peroxide or carbamide peroxide to oxidize stains, and potentially a laser to enhance their effects, Dr. Huang explains) are going to make them a stark, dazzling white. 

Even if you had the whitest teeth on planet Earth from the moment you were born, there is no guarantee that you can return to that tone after stains begin to form. You may get close, but "it's difficult to assess how white the teeth will get [in a professional treatment]," says Dr. Veytsman. "It's not like I have this setting that says, okay this is how white you want to be. It's more about doing the procedure and oxidizing the stains off the external layer of the teeth." 

The bottom line: You might be stuck with this tooth color

So, what if your natural tooth color will never allow you to reach that stereotypical white smile? Most people can't. Luckily, the color of your teeth are typically not an indicator of your overall health or hygiene, though specific habits like smoking can cause dramatic staining. Still, that's not to say people should ignore teeth-whitening products or services altogether. Dr. Reid explains that if you never address tooth staining, it's possible your teeth will dull up to 15 shades darker than your natural color over your lifetime. How does one address it, with all the chips seemingly stacked up against us? It may mean visiting a professional for an in-office service, trying an at-home option, or simply using a whitening toothpaste and sipping your morning coffee through a straw to bypass your teeth.

For the most part, though, tooth color is primarily an aesthetic concern, and visiting your dentist for annual checkups will confirm that your teeth are healthy on the inside and out —  regardless of how they look. In the end, it usually can't hurt to provide your teeth with movie star-worthy care each and every day.

Read more about oral care here:

• What I Wish I'd Known Before Getting a "Permanent" Retainer"

• Maybe Taping Your Mouth Shut Overnight Isn't A Good Idea

• Teeth Scaling Is Pure, Scrape-y Satisfaction For My Brain

Now, watch Rachel Bilson's beauty routine:

Originally Appeared on Allure